Polyester coated wire

ABSTRACT

A wire insulated with an impervious oxybenzoyl polyester coating which can be produced by drawing the wire having a porous coating through a die.

United States Patent [191 Cottis et al.

[451 Dec. 18, 1973 POLYESTER COATED WIRE Inventors: Steve G. Cottis, Amherst; Bernard E. Nowak, ancaster; James Economy, uffalo, all of N.Y.

Assignee: The Carborundum Company,

Niagara Falls, NY.

Filed: Oct. 7, 1971 Appl. No.: 187,339

Related U.S. Application Data Division of Ser. No. 828,652, May 28, I969, Pat. No. 3,669,738.

U.S. CI. [17/232, 117/161 K Int. Cl B44d l/42, C09d 3/68 Field of Search ll7/232, 128.4, 16] UC,

Primary ExaminerWilliam D. Martin Assistant ExaminerHarry J. Gwinnell Att0rneyDavid E. Dougherty et al.

[5 7] ABSTRACT A wire insulated with an impervious oxybenzoyl polyester coating which can be produced by drawing the wire having a porous coating through a die.

8 Claims, 2 Drawing Figures INVENTORS ST COT STEVE GU TIS BERNARD EDWARD NOWAK JAMES ECONOMY 'PATENIEUUECI a 1915 POLYESTER COATED WIRE This is a division of application Ser. No. 828,652, filed May 28, 1969, now US. Pat. No. 3,669,738, issued June 13, 1972.

Wires electrically insulated with polymers are wellknown in the art. Two widely used classes of polymers are polyesters the most common example of which is polyethyleneterephthalate commercially available as Mylar and fluorocarbon polymers such as polytetrafluoroethylene commercially available as Teflon. While such insulated wires have found wide acceptance they are generally unsuitable for carrying high frequency currents and/or for operation at high temperatures such as those above 600F. When operating under these conditions undesirable degradation of the polymer coating occurs decreasing its electrical resistance and rendering the wire susceptible to short circuits and exposure to the elements.

According to recently discovered techniques it is now possible to produce high molecular weight oxybenzoyl polyesters which have advantageous physical and chemical properties rendering them especially suitable for use as insulation on electrically conductive wires. However, it has heretofore been impossible to coat wires with these oxybenzoyl polyesters due to their tendency to thermally degrade at temperatures below their melting point. Notwithstanding this difficulty,

however, these polyesters are resistant to temperatures up to and sometimes exceeding 700F.

It is therefore an object of the present invention to provide an improved insulated wire and process for producing such which is substantially free of the disadvantages of the prior art.

Another object is to provide an improved process for producing an insulated wire which functions satisfactorily at high temperatures and/or high frequencies.

A further object is to provide an improved wire insulated with an oxybenzoyl coating and an improved process for producing such.

Yet another object is to provide an improved process for producing a wire insulated with an impervious oxybenzoyl polyester.

Additional objects and advantages of the present invention will be apparent to those skilled in the art by reference to the following detailed description and drawings wherein:

FIG. 1 is a schematic representation of an apparatus suitable for practicing the process of the present invention and FIG. 2 is a sectional view of a wire of the present inbenzoyl polyester coating can be produced by drawing the wire having a porous coating through a die.

A preferred process of the present invention comprises the steps of forming a porous coating of granular oxybenzoyl polyester on the wire and then drawing the coated wire through a die to render the porous coating impervious.

Referring now to the drawings and in particular to FIG. 1 there is schematically shown an apparatus suitable for practicing the process of the present invention. The apparatus 10 comprises a heatingsection 11 having burners l2 and 13; a container 14 adapted to hold an oxybenzoyl polyester 15; and a die 16. In operation a wire 17 is caused to move in the direction of the arrow 18 by any suitable means not shown. The burners l2 and 13 heat the wire 17 to the desired temperature whereupon the wire 17 passes through a hole in the bottom of the container 14 and then contacts the polyester 15. The granules of polyester 15 adhere to the wire forming a porous coating 19 having a rough surface. The wire 17 having the coating 19 then passes through the die 16 wherein the coating 19 is subjected to shearing action which decreases the porosity of the coating 19 to produce a smooth impervious coating 20 on the wire 17. The diameter, d of the die 16 is greater than the diameter, d of the wire 17 but is less than the diameter, d;,, of the wire 17 with rough coating 19. The process can be practiced simultaneously i.e., with the container 14 in contact with the die 16, which can also be heated.

The temperature of the wire 17 prior to contacting the polyester 15 is critical and is usually 200 to 1200F and is preferably 500 to 1100F. At temperatures much below these ranges the polyester 15 does not adhere to the wire 17 whereas at temperatures much above these ranges thermal degradation of the polyester occurs. It will be readily apparent that the heating can be accomplished by other means such as electrical resistance or electrical induction.

The wire 17 can be a low resistance material such as silver or preferably copper, or can also be a high resistance material such as tungsten or Nichrome. The wire 17 can also have a coating or can be subjected to conventional pretreatments.

The oxybenzoyl polyesters useful in the present invention are generally those of repeating units of For- One preferred class of oxybenzoyl polyesters are those of Formula II:

ekale doned, the disclosure of which is incorporated herein I by reference.

Another preferred class of oxybenzoyl polyesters are copolyesters of recurring units of Formulae I, III and wherein X is Oor SO m is or 1; n is 0 0r 1;

to 600; and preferably 30 to 200. The carbonyl groups of the moiety of Formula I or Ill are linked to the oxy groups of a moiety of Formula I or IV: the oxy groups of the moiety of Formula I or IV are linked to the carbonyl grotips of the moiety of Formula I or III.

The preferred copolyesters are those of recurring units of Formula V:

i I I 7 M3 Q Q The synthesis of these polyesters is described in detail in US. Pat. Application Ser. No. 828,484, filed May 28, 1969 now US. Pat. No. 3,637,595, issued Jan. 25, 1972 which is assigned to the assignee of this application and the disclosure of which is incorporated herein by reference.

The polyesters useful in the present invention can also be chemically modified by various means such as by inclusion in the polyester of monofunctional reactants such as benzoic acid or trior higher functional reactants such as trimesic acid or cyanuric chloride. The benzene rings in these polyesters are preferably unsubstituted but can be substituted with noninterfering substituents examples of which include among others halogen such as chlorine or bromine, lower alkoxy such as methoxy and lower alkyl such as methyl.

The polyesters useful in the present invention can be employed in their pure form, mixed with one another or with a wide variety of organic and/or inorganic fillers which do not affect their electrical properties. Examples of suitable organic fillers include among others polyhalogenated addition polymers such as polytetrafluoroethylene and condensation polymers such as polyimides. Examples of suitable inorganic fillers include glass fibers. These fillers can comprise up to 70 wt percent of the combined weight of polyester and filler.

EXAMPLE 1 A mixture of 856 g of phenyl para-hydroxybenzoate, 0.015 g of tetra-n-butyl orthotitanate and 1800 g of a polychlorinated polyphenyl solvent (b.p. 360370C) is heated, with constant stirring and under an atmosphere of flowing nitrogen, at l70190C for four hours and then at 340360C for 10 hours. Early in this heating cycle the mixture becomes a homogeneous EXAMPLE 2 This example illustrates the synthesis of a copolyester useful in the present invention.

The following quantities of the following ingredients are combined as indicated.

Quantit Item Ingredient Grams Mules A Phydroxybenzoic Acid l38 l B Phcnyl acetate l L25 C Thcrminol 77 500 D Diphenyl Tcrephthalatc 3 l 8 l E Hydrogen Chloride F Hydroquinone Ill l.0l G Therminol 77 500 Items A D are charged to a four-necked, round bottom flask fitted with a thermometer, a stirrer, combined nitrogen and HCl inlet and an outlet connected to a condenser. Nitrogen is passed slowly through the inlet. The flask and its contents are heated to 180C whereupon HCl is bubbled through the reaction mixture. The outlet head temperatures is kept at l lO-l20C by external heating during phydroxybenzoic acid, phenyl acetate ester exchange reaction.

The flask and its contents are stirred at l 80l and the mixture stirred at 220 for 3.5 hours. Up to this point, 159 grams of distillate are collected in the condenser. Item F is then added and the temperature gradually increased from 220C to 320C over a period of 10 hours (lOC/hr.). Stirring is continued at 320C for 16 hours and then for three additional hours at 340C to form a slurry. The total amount of distillate, consist- EXAMPLE 3 The polyester of Example 1 is placed in a container 14 of an apparatus 10 similar to that shown in FIG. 1. The wire 17 which is of copper is heated to a temperature of 600 F. and passed through the polyester at a speed of approximately 5 ft./sec., to form a coated wire which is passed through a die 16 to render the coating smooth and impervious. The resultant coated wire functions satisfactorily as an electrical conductor and when immersed in hydrochloric acid gives no indication of attack of the wire 17. A wire similarily produced except that it is not passed through the die 16, bubbles and shows other evidence of attack of the wire 17 through the coating 20, when immersed in hydrochloric acid.

EXAMPLE 4 The procedure of Example 3 is repeated employing the same times, temperatures and conditions with the exception that the polyester of Example 1 is replaced by the polyester of Example 2 with similar results.

EXAMPLE 5 The procedure of Example 3 is repeated employing the same times and conditions except that the container 14 and burners 12 and 13 and the container 14 are removed and the oxybenzoyl polyester of Example 1 is flame sprayed onto the wire 17 with similar results.

Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as describedabove and as defined in the appended claims.

We claim:

1. A wire insulated with an impervious coating consisting essentially of an oxybenzoyl polyester, said oxybenzoyl polyester have a molecular weight of at least about 3500 and being selected from the group consisting of:

a. A polyester having the formula wherein R is benzoyl, lower alkanoyl or hydrogen; R is phenyl; and p is an integer from 30 to 200; and

b. A polyester consisting essentially of recurring structural units of Formulas I, III and IV wherein X is -O-or SO m is 0 or 1; n is 0 or 1; q:r :15 to 10; p:q 1:100 to 100:]; p +q r 30 to 200; the carbonyl groups of the moiety of Formula I or III are linked to the oxy groups of the moiety of Formula I or IV; and the oxy groups of the moiety of Formula I or IV are linked to the carbonyl groups of the moiety of Formula I or III.

2. An insulated wire as set forth in claim 1, said wire being copper.

3. An insulated wire as set forth in claim 1 wherein said oxybenzoyl polyester has a molecular weight of from 3500 to 25000 and has the formula R C) E -QR T Q J.

wherein R is acetyl or hydrogen; R is phenyl; and p is an integer from 30 to 200.

4. An insulated wire as set forth in claim 3 wherein R is hydrogen.

5. An insulated wire as set forth in claim 1 wherein said oxybenzoyl polyester has a molecular weight of from 3500 to 25,000 and consists essentially of recurring structural units of Formulas I, III and IV.

6. An insulated wire as set forth in claim 5 wherein m is 0.

7. An insulated wire as set forth in claim 5 wherein n is 0.

8. An insulated wire as set forth in claim 5 wherein said oxybenzoyl polyester consists essentially of recurring units of the formula I Q Q 

2. An insulated wire as set forth in claim 1, said wire being copper.
 3. An insulated wire as set forth in claim 1 wherein said oxybenzoyl polyester has a molecular weight of from 3500 to 25000 and has the formula
 4. An insulated wire as set forth in claim 3 wherein R1 is hydrogen.
 5. An insulated wire as set forth in claim 1 wherein said oxybenzoyl polyester has a molecular weight of from 3500 to 25, 000 and consists essentially of recurring structural units of Formulas I, III and IV.
 6. An insulated wire as set forth in claim 5 wherein m is
 0. 7. An insulated wire as set forth in claim 5 wherein n is
 0. 8. An insulated wire as set forth in claim 5 wherein said oxybenzoyl polyester consists essentially of recurring units of the formula 